Wedge flow coolant nozzle for grinding machine

ABSTRACT

A coolant distributing apparatus for a grinding machine has a first casing above the workpiece adjacent the periphery of the grinding wheel for receiving coolant under pressure and directing it into the grinding wheel to be released at the operating zone, and a second casing designed to receive and contain the workpiece, the second casing forming a work chamber thereabout for maintaining the coolant around the outer periphery of the workpiece.

United States Patent 1191 Matson Sept. 10, 1974 WEDGE FLOW COOLANT NOZZLE FOR 2,899,781 8/1959 Williams 51/267 2,914,892 12/1959 Fouquet 51/267 GRINDING MACHINE 3,712,001 1/1973 Kaesemeyer et al 51/267 [75] Inventor: Charles Bernard Matson,

Cincinnati, Ohio [73] Assignee: Cincinnati Milacron Inc., Primary Exammer-0thell Slmpson Cincinnati, Ohio [21] Appl. No.: 348,988 q A coolant d1str1but1ng apparatus for a grinding machine has a first casing above the workpiece adjacent [52] US. Cl. 51/267 the periphery of the grinding whee for receiving COOL [51] Int. Cl B24b 55/02 am under pressure and directing it into the grinding [58] Field of Search 51/267; wheel to be released at the Operating Zone and a 29/DIG- 55-Dlc 1316- 63-1316 69; 0nd casing designed to receive and contain the work- 90/11 R piece, the second casing forming a work chamber thereabout for maintaining the coolant around the [56] References cued outer periphery of the workpiece.

UNITED STATES PATENTS 1,286,518 12/ 1918 Brassill 51/267 4 Claims, 6 Drawing Figures i li WEDGE FLOW COOLANT NOZZLE FOR GRINDING MACHINE BACKGROUND OF THE INVENTION The present invention relates to an improved workpiece cooling apparatus for grinding machines.

During a typical grinding operation, the periphery of the grinding wheel may reach surface speeds, for example, of 4,000 to 16,000 feet per minute. The speed will depend on the workpiece specifications. Most grinding wheels are porous and will act as centrifugal pumps while others cause the air layer adjacent to the surface to reach high speeds. The air flowing from the wheel develops a significant pressure which restricts the flow of coolant into the cutting zone. Unless the liquid is channeled and drivn under pressure into the cutting zone, it is often difiicult to achieve adequate cooling or lubricating action.

To minimize the speed of the air film layer adjacent the wheel caused by the air at the periphery following the surface of the wheel, it is known to provide a casing extending from a coolant liquid inlet to the point just above the workpiece. The casing defines the chamber in communication with the grinding wheel, the liquid being driven by the grinding wheel to the bottom of the chamber where is escapes into the cutting zone. It is further known that the high velocity air surrounding the periphery of the workpiece may be diverted from entry into the chamber by use of an air scraper. The coolant chamber and air scraper are disclosed and fully explained in US. Pat. No. 3,325,949 of Robert C. Fischer, entitled Guard System for High Speed Grinder, issued June 20, 1967 and assigned to the present assignee.

The object of the present invention is to modify the system disclosed by Fischer in order to reduce the amount of air being pumped through the grinding wheel by centrifugal force and to utilize the centrifugal force of the wheel as a coolant pump.

It is another object of the present invention to provide a second chamber for containing the workpiece and maintaining the coolant flow around the periphery of the workpiece during the grinding operation to enhance the cooling capabilities during the period of time that a portion of the workpiece is not exposed to the grinding wheel.

Other objects and features of the present invention should be readily apparent by reference to the following specification considered in conjunction with the accompanying drawings forming a part thereof. It is to be understood that any modification may be made in exact structural details here shown and described, within the scope of the amended claims without departing from or exceeding the scope and spirit of the invention.

SUMMARY OF THE INVENTION The present invention is an improved coolant apparatus for a machine tool having a grinding wheel to engage a workpiece at an operating zone, wherein the coolant supply means provides coolant under pressure to a region of the periphery of the wheel above the operating zone. The first casing located above the workpiece and adjacent to the periphery of the grinding wheel defines a fluid chamber in fluid communication with the supply means and extending along the periphery of the wheel from the supply means toward the workpiece. The chamber is of the configuration forcing coolant into the grinding wheel at a point above the grinding zone. The coolant is released by centrifugal force at the point of grind. A second casing is designed to receive the workpiece and form a work chamber thereabout for directing and maintaining coolant around the outer periphery of the workpiece. The primary coolant exhaust in the present system is back through the grinding wheel and out of the grinding zone and work chamber.

In this manner, the entire workpiece is inundated with coolant during the grinding operation. Coolant is released at the point of grind and containedin the environment surrounding the workpiece during the grinding operation. The coolant is maintained under pressure during the entire operation and provides adequate cooling the workpiece during grind.

The fluid chamber is generally wedge shaped having a reducing volume as it approaches the point of exit and enters the grinding zone. In this manner, fluid forced into the top of the chamber under pressure is directed into the grinding wheel, thus loading the wheel and releasing the fluid at a point near or at the grinding zone as a result of the centrifugal action of the wheel on the entrapped coolant. The work chamber then receives the released fluid and inundates the workpiece with coolant during grind.

The invention can further include an air scraper positioned above the first casing and next to the wheel to deflect the volume of air flowing around the periphery of the wheel from thereby blocking the air driven by the grinding wheel entering the fluid chamber and mingling with the fluid, reducing its effectiveness, as shown and described in the aforementioned Fischer patent.

An alternative to the air scraper is a unique fluid pressure sea] utilizing a stream of fluid to form a combination air scraper and fluid seal against leakage.

Thus, the present invention provides an improved coolant apparatus designed to inundate the workpiece with coolant fluid during grinding, while releasing a substantial portion of the fluid from the wheel at the point of grind.

THE DRAWINGS FIG. 1 is an elevational view showing a grinding machine utilizing the preferred embodiment of the present invention.

FIG. 2 is an enlarged fragmentary view, partially in section, showing the detail of FIG. 1.

FIG. 3 is a section view taken along lines 33 of FIG. 2.

FIG. 4 is a fragmentary view of FIG. 2 showing a portion of the preferred embodiment with the workpiece removed.

FIG. 5 is the rear view of that portion of the preferred embodiment shown in FIG. 4.

FIG. 6 is a section view taken along lines 6-6 of FIG. 2.

DETAILED DESCRIPTION There is shown in FIG. 1 a grinding machine 10 having a wheelhead 12 supporting and driving a grinding wheel 14. The grinding wheel 14 rotates in the direction of the arrow 16 and feeds into the workpiece 18 by sliding the entire wheelhead 12 to the left as shown on slide 20 in a manner well-known in the art. The headstock 22 contains a spindle 24, see FIG. 4, which drives the workpiece 18 during the grinding operation. Special shoes are generally used to hold the workpiece, but for simplicity a magnetic chuck type spindle 24 is utilized herein. The endface 26 of the spindle 24 is an electromagnet designed to attract and secure the workpiece 18 to the spindle 24 as it is rotated during the grinding operation.

The loading fixture 28 contains the coolant apparatus of the present invention. The loading fixture may include an automatic loading feature if desired without departing from the spirit of the invention. However, a fixture requiring manual loading has been used in the present embodiment for simplicity of disclosure.

As shown in FIG. 2, the coolant apparatus of the present invention includes a casing 29 forming a wedge shaped fluid channel 30 utilizing the peripheral surface of the grinding wheel 14 as a wall thereof. Coolant is supplied under pressure via coolant supply tube 32. As the grinding wheel 14 rotates in the direction of arrow 16 coolant is forced into the coolant chamber 30. By utilizing the reducing volume of the wedge shaped chamber 30 the coolant is naturally forced into the grinding wheel 14. Leakage about the side of the wheel is held to a minimum by utilizing the grinding wheel 14 as the finishing tool to generate the final size of the chamber 30, see particularly FIG. 3. In this manner, the inner walls 34 and 36 of the chamber 30 conform substantially to the size of the grinding wheel 14. Thus, the only substantial release point for the coolant is in the operating zone 38 in which coolant is released as a result of the centrifugal force generated by the rotating grinding wheel 14. By enclosing the workpiece 18 in a second chamber 40, the workpiece is inundated with released coolant during grinding.

The workpiece 18 is rotated by the spindle 24, and located and secured during grind by suitable means, for example, the stepped portion 42 and electromagnet at endface 26 of the spindle 24. A door 44, either slideably attached or hinged to the work chamber wall 46 substantially seals the front opening of the work chamber 40 during grinding operations.

In FIG. 5, a partial view of the back wall 48 of the work chamber 40 is illustrated. It contains gasket means 50 having an opening substantially confonning to the diameter of the spindle 24 thus minimizing leakage of coolant during the grinding operation. The gasket 50 is held in place by a rigid plate 52 made of any suitable means and secured in place by mounting screws 54. During a grinding operation when coolant is released into the operating zone through the wheel 14 it is maintained in the work chamber 40 thereby inundating the entire workpiece 18 during grind. In this manner, the workpiece 18 is maintained at a substantially lower temperature than with utilization of prior art coolant devices. The coolant is substantially exhausted back through the grinding wheel 14 as well as through leakage around gasket 50 and door 40. Thus, it is not necessary to have a leak-proof system in the preferred embodiment of the invention.

It should further be understood that the coolant chamber 30 can be utilized with or without the work chamber 40. Thus, it is desirable to manufacture two chambers as separate pieces, then secure them to each other by any suitable securing means, see mounting bolts 60.

Since the coolant means froms a part of the workholding fixture 28, it is desirable to permanently secure the fixture 28 to the headstock 22, machine base, or other suitable machine members. This may be accomplished by any suitable means, for example, the mounting bolts 58 shown in FIG. 2. Securing the work holding means in this manner is particularly useful when locating shoes are utilized to locate the workpiece 18 rather than the chuck mounting of the illustrated embodiment, which is typical of many grinding operations.

Manufacturing the coolant chamber in this manner, permits use of the invention in a variety of grinding operations other than the type illustrated, for example, center type or centerless machining.

An air scraper may also be utilized with the present invention, see particularly FIG. 2. The air scraper is substantially shown and described in the aforementioned Fischer patent and may be secured to the top edge of the coolant chamber. In the present invention a unique air scraper arrangement is illustrated, utilizing a pressure fluid seal. In this case a coolant supply means 72 is secured to the top edge 70 and extends to the far wall 74 of the coolant chamber 30. Whencoolant is supplied under pressure through coolant supply means 72 a coolant stream flowing out from the coolant supply means provides a fluid air scraper, deflecting air flow following the wheel. In this manner, any air following the periphery of the grinding wheel forces the coolant into the coolant chamber while at the same time the air flow is being diverted away from the coolant chamber by the presence of the fluid under pressure. This aids in directing the largest portion of the coolant into the grinding wheel at the point above grind thereby permitting the grinding wheel to act as a centrifugal pump forcing the coolant out at the point of grind. The fluid seal slso provides a wall of coolant between chamber 30 and the environment. This minimizes leakage of coolant supplied by supply means 32 through the top of chamber 30.

A small gap 76 is present below the point of grind thus permitting the exhausting fluid to flow along the face of the grinding wheel for a certain distance. This gap permits the adequate cooling of the grinding wheel after the point of grind has been passed. A plate 78 has been attached to the bottom edge 80 of the coolant chamber 30. This reduces the gap size at the end of the chamber 30 thus increasing the pressure inside the work chamber 40 by reducing the amount of fluid that can flow through the gap. It should be understood that the fluid seal arrangement described above would work equally as well as an alternative to plate 78. The addition of the auxiliary coolant supply 72 also aids in reducing the peripherial air speed thus requiring only that the pressure of the fluid through the supply means 32 be able to overcome the centrifugal force of the wheel in supplying coolant to the work zone 38.

While particular embodiments have been illustrated and described in substantial detail, it should be understood that the foregoing is merely illustrative and is not intended to limit the spirit and scope of the appended claims. I

What is claimed is:

1. In a machine tool having a porous grinding wheel acting as a centrifugal pump, the wheel engaging a workpiece at an operating zone, a coolant apparatus comprising:

a. a coolant supply means supplying coolant under pressure to the region of the periphery of the wheel above the operating zone;

b. a first casing above the workpiece and adjacent to the periphery of the grinding wheel for receiving the coolant under pressure, said casing in fluid communication with said supply means defining a fluid chamber and extending along the periphery of the wheel from said supply means towards the workpiece for forcing coolant into the wheel at a point above the operating zone; and

c. an air scraper positioned above said first casing and in a position adjacent with the wheel to deflect the volume of air flowing around the periphery of the wheel thereby blocking the air driven by the grinding wheel from entering said fluid chamber.

2. In a machine tool having a porous grinding wheel acting as a centrifugal pump, the wheel engaging a workpiece at an operating zone, a coolant apparatus comprising:

a. a coolant supply means supplying coolant under pressure to the region of the periphery of the wheel above the operating zone;

b. a first casing above the workpiece and adjacent to the periphery of the grinding wheel for receiving the coolant under pressure, said casing in fluid communication with said supply means, defining a fluid chamber and extending along the periphery of the wheel from said supply means towards the workpiece for forcing coolant into the wheel at a point above the operating zone;

c. a second casing designed to receive the workpiece and form a work chamber thereabout for directing the coolant around the periphery of the workpiece; and

d. a scraper positioned below said second casing and in a position adjacent with the wheel to reducev the volume of fluid flowing through the gap between said second casing and the wheel.

3. The apparatus of claim 1 wherein said air scraper further comprises a fluid pressure seal for minimizing the escape of fluid from said first chamber.

4. The apparatus of claim 2 wherein said scraper further comprises a fluid pressure seal. 

1. In a machine tool having a porous grinding wheel acting as a centrifugal pump, the wheel engaging a workpiece at an operating zone, a coolant apparatus comprising: a. a coolant supply means supplying coolant under pressure to the region of the periphery of the wheel above the operating zone; b. a first casing above the workpiece and adjacent to the periphery of the grinding wheel for receiving the coolant under pressure, said casing in fluid communication with said supply means defining a fluid chamber and extending along the periphery of the wheel from said supply means towards the workpiece for forcing coolant into the wheel at a point above the operating zone; and c. an air scraper positioned above said first casing and in a position adjacent with the wheel to deflect the volume of air flowing around the periphery of the wheel thereby blocking the air driven by the grinding wheel from entering said fluid chamber.
 2. In a machine tool having a porous grinding wheel acting as a centrifugal pump, the wheel engaging a workpiece at an operating zone, a coolant apparatus comprising: a. a coolant supply means supplying coolant under pressure to the region of the periphery of the wheel above the operating zone; b. a first casing above the workpiece and adjacent to the periphery of the grinding wheel for receiving the coolant under pressure, said casing in fluid communication with said supply means, defining a fluid chamber and extending along the periphery of the wheel from said supply means towards the workpiece for forcing coolant into the wheel at a point above the operating zone; c. a second casing designed to receive the workpiece and form a work chamber thereabout for directing the coolant around the periphery of the workpiece; and d. a scraper positioned below said second casing and in a position adjacent with the wheel to reduce the volume of fluid flowing through the gap between said second casing and the wheel.
 3. The apparatus of claim 1 wherein said air scraper further comprises a fluid pressure seal for miNimizing the escape of fluid from said first chamber.
 4. The apparatus of claim 2 wherein said scraper further comprises a fluid pressure seal. 